Gas actuated vapor feed system



.A r l 22, 1969 A. MOORE I GAS ACIUATED'YAIPOR FEED SYSTEM Sheet;

Fil ed Nov. 9,196?

INVENTOR. 08627? 0- #00:. Jar W A'rra wry zuewr April 22, 1969 R. A.Mock; 3,439,501 v I GAS ACTUATED VAPOR'FEED SYSTEM Filed Nov. 9, 1967Sheet INVENTOR. 08527 1?. Moon?! By 44 9 W 07'7'042 5 United Stes PatentPatented Apr. 22, 1969 US. Cl. 60203 4 Claims ABSTRACT OF DISCLOSURE Ina gas actuated feed system which has a liquid or a liquid with solidstherein stoied in a tank, an oscillation damping porous metalplug-iSiprovided in the end of the supply tube leading to a vafphi'izer, attached to a nozzle. The nozzle end of the vapqrizer isheated and radiation fins are located on the vaporizer to provide theproper temperature gradient alon the vaporizer. An enlarged liquidsupply hole is provid near the end of the vaporizer. Blind holes areprovide adjacent the liquid supply holes in the vaporizer to h ll,:excess liquid during oscillations of the liquid in the liquid supplytube.

Background of the invention Various systems have been used for meteringflow in the vapor feed systems used in magnetoplasma dynamic thrustors.The most common of these requires the heating of the entire storagecontainer to a temperature high enough so that the vapor pressure causesthe discharge orifice to choke. Under these conditions, the flow-rate isproportional to vapor pressure which in turn is a function of the liquidtemperature.

Two major disadvantages ot this system are that the vapor pressure isvery sensitive to temperature and for long periods in space theelectrical }power required is excessive.

Another method is to feed; the liquid bypositive displacement such as byexten'ding nested bellows. This method surfers from the pr oblem oftemperature and pressure variations which cause the system to beunsteady and inaccurate due t6 vapor pressure variations dueto volumedisplacement of the bellows due to these variations.

Summary of the invention According to this inventioiiga gas-actuatedfeed-system is used. The major difficultyi with a gas-actuated feedsystem is the stabilization oi the vapor flowing from the sonic nozzleorifice due to, the tendency of the liquid column to oscillate at afrequency of 1-10 cycles per second. The unique featurepf this inventionrelates to the means of stabilization otfthe vapor flowing from thenozzle. This is accomplished by incorporating a porous plug in thetinlettube leading'to the vaporizer, the provision of blind holes in thevaporizer parallel to the vaporizer holes and by the establishment ofthe proper temperature gradient in the vaporizer.

Brief description of the drawing FIG. 1 is a schematic diagram of agas-actuated vapor feed system according to the invention;

FIG. 2 is an enlarged view of the vaporizer unit of the device of FIG.1; r

F1613 is a sectional view of the device of FIG. 2 along the line 3--3;and

FTG. 4 is an enlarged sectional view of the device of FIG. 2 along theline 4-4.

Description 0 the-preferred embodiment Reference is now made to FIG. 1of the drawing which shows a liquid supply tank 10 having a heating coil12 surrounding the tank to melt any solid material in the tank. Thepower requirements for this coil are not as great as for the systemdescribed abovei-l The tank may contain various liquids or mixtures of iquid and solid particles, but in use for which it was constructed thematerial 14 used is liquid lithium. The heating coil 12 may not beneeded when no solid particles {are in the liqiiid. A vaporizer shownschematically at 16 is com nected to the tank 10 by means of aliquidgffeed tube 1 7 .j'fA porous metal plug 18 of a material such astungsteii" is located in. the endof tube 17 withinl 'the tank 10 forfiltering and damping oscillations withiii the tube 17. ';I A gas underpressure such as, argon is sii'pplied to the tank 10 through an inlettube 22. A pressure regulator 24 and pressure gauge 25"ar'eT providedirijthe inlet tube 22. The pressure regulator may be either manual orautomatic depending upon the particular use of the ap iaratus.

Since the porous plug 18 will not damp out all oscillatioris, aplurality of blind holes 27, shown in FIGS. 3 an j4, are provided in thevaporizer and are located around the supplyvholes 28. 7

The end of the vaporizer 16 is connected to the anode 29 }hf the dynamicthrustor The anode is heatedby the discharge between cathode '30 andanode 29 and this heat is conducted to the vaporizer 16. If thevaporizer 'is used forjotherpurposes, a separate heat source such as anelet'itr'ical heating element, may be provided adjacent the endijljofthe vaporizer 16. 4

Radiation; fins 31 are spaced along the outer surface of j the vaporizer16 to establisha proper temperaturegradient along its length An enlargedpassage 33is provided in the vaporizer leading to the annular nozzleorifice 34in anode 29-. 1 The oscillations of the liquid column arestabilized by 'holes 27 to supply any deficiency of vapor from supplyholes 28.

If the oscillations are such that an excess amount of fluid enters theblind holes, though not shown, a return to the liquid supply may beprovided from these holes.

There is thus provided a vapor feed system that does not have thedisadvantages of prior art systems.

While a certain specific embodiment has been described, it is obviousthat numerous changes may be made without departing from the generalprinciples and scope of the invention.

claim: 1

11. A gas-actuated vapor feed system comprising: a liquid supplycontainer having vaporizable liquid therein; a vaporizer havinga sonicnozzle connected at one end thereof; a supply tube having one endimmersed in said liquid and the other end connected to said vaporizer atthe end thereof opposite said nozzle; a porous metal plug in the end ofsaid supply tube immersed in the liquid; said vaporizer having at leastone liquid passage therethrough; an enlarged liquid passage in saidvaporizer at the end adjacent" said nozzle; means for heating the end ofsaid vaporizer adjacent said nozzle whereby a temperature gradient isprovided along the length of said vaporizer; means for supplying a'gasunder pressure to said supply container whereby liquid is supplied tosaid vaporizer; means for controlling the .pwsure of said gas to therebycontrol the flow of said liquid.

in the establishment of the temperature gradient along the length of thevaporizer.

References Cited UNITED STATES PATENTS 3,350,884 11/1967 Colombani60-203 3,359,733 12/1967 Forbes 60202 3,359,734 12/ 1967 Ferric et al.60203 10 CARLTON R. CROYLE, Primary Examiner.

US. Cl. X.R., 219-l21

